1. Field of the Invention
The invention relates to a machining equipment, and more particularly to a workpiece holding device for a machining equipment in order to facilitate the high-precision machining of a six-sided workpiece.
2. Description of the Related Art
FIG. 1 shows a conventional machining equipment to mainly comprise a machine frame 10, a movable shaft assembly 11 and a workbench 13. The movable shaft assembly 11 is provided on one side of the machine frame 10. A clamping member 111 is provided on one end of the shaft assembly 11. A cutting tool 14 is attached to the shaft assembly 11 via the clamping member 111. A workpiece (not shown) is to be secured on top of the workbench 13. A power means (not shown) rotatably drives the shaft assembly 11 to move the cutting tool 14 in a direct line of motion relative to the workpiece. The workbench 13 is then rotated so as to align one side of the workpiece with the line of motion of the cutting tool 14. However, even if the workbench 13 has been rotated for 360 degrees, only four of the six sides of a rectangular workpiece can be machined without moving the workpiece relative to the workbench 13.
Although present computer numeric controlled (CNC) machining equipments can also machine the top side (fifth side) of a rectangular workpiece, the sixth side of the workpiece which is in contact with the workbench cannot be machined without adjusting the position of the workpiece on the workbench.
When moving the workpiece relative to the workbench, utmost care must be taken so that the side to be machined is aligned with the line of motion of the cutting tool so as to maintain the same depth of machining. It is thus possible that the machining precision will be affected whenever the position of the workpiece is adjusted.
Recent numeric controlled (NC) machining equipments can perform different machining operations on the same workpiece upon the keying-in of a string of instructions. Thus, the position of the workpiece on the workbench is further adjusted so that the desired machining operation can be conducted on the selected part of the workpiece. Therefore, the machining precision and the succeeding machining operations will be affected if the workpiece is improperly placed on the workbench when the sixth side of the workpiece is machined.